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Beckman Scholar Jared Balik Publishes: High interspecific variation in nutrient excretion within a guild of closely related caddisfly species

Friday, May 25, 2018

Learn more about what Beckman Scholar Jared Balik (Allegheny College '14) has been working on:

ABSTRACT:

Understanding the amount of variation in functional traits between closely related species within guilds is critical for understanding links between
community composition and ecosystem processes. Nutrient excretion is an important link between animals and their environments, and aquatic invertebrate
communities can supply a considerable proportion of ecosystem nutrient demand via excretion. We quantified nitrogen (N) and phosphorus (P) excretion
rates of 10 species of larval caddisflies that inhabit high-elevation ponds and wetlands to determine the magnitude of variation in nutrient excretion
within this guild. We found considerable interspecific variation in biomass-specific excretion of nitrogen (eightfold differences), phosphorus
(sevenfold differences), and the stoichiometric N:P ratios (fivefold differences). Through a meta-analysis, we compared the variation within this
guild to the variation found in other family-level species assemblages to determine the overall range in the variation of nutrient excretion that
could be expected across guilds and to determine whether the variation in this caddisfly guild is comparatively extreme, average, or low. The meta-analysis
revealed a large range in variation among guilds, and comparatively, the variation within this caddisfly guild is high for N excretion and intermediate
for P excretion. The considerable variation within guilds revealed by our metaanalysis suggests that functional redundancy among guild members
is difficult to predict. Thus, some natural or human-caused species gains or losses within biological groupings such as guilds and trophic levels
could have little or no effect on ecosystem processes, whereas others could have very large effects.

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